Electric furnace.



E. K. SCOTT.

ELECTRIC FURNACE.

APPLICATION HLED Fa. 25, 191e.

l, Patented 0@t.'31,1916.

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ERNEST KILBURN SCOTT, OF BELVEDERE, ENGLAND, SSIGNOR TO ATMOSPHERIC NITRATES (KILBURN SCOTT PATENTS) LIMITED, OF MANCHESTER, ENGLAND.

ELECTMC FURNASE.

Specification of Letters Patent.

llaa-.tenten 0st. 31, 1916.

Application filed February 25, 1916. Serial No. 80,437.

To HU 'whom t may con/cra lle it lo vwn that l, llnx'ns'r Kinnnnr Sco'r'r` subject of the. King! ot' llneland, res siding,V at Belvedere` Kent. in llnt'land, have invented certain new and use't'ul lmprove ments in Electric ll`urnaces, ot which the tollowing is a specification.

This invention relates to electric 'furnaces and has particular reterence to turna-ces 'tor the. fixation o'tI nitrogen from the atmos phere.

The primary object ot the invention is to increase the elliciency ot such furnaces by insuring' that practically all the air which enters the furnace passes through the arc. This object is attained according to this invention by the employment ot' electrodes so shaped and disposed that they inclosc a een tral space, which is preferably in the 'torni ot' an inverte-,o cone. arcingf gaps being provided between adjacent electrodes.

ln a preferred arrangement each electrode is provided with a shield-like plate which forms the active portion ot the electriale the shape and proportions ot each plaie beine' such that when the electrodes are arranged in their operative position in the turnace.y the plates inclose a central space to which vair can pass through gaps between the sides or edges ot adjacent plates. These spaces or slots aie. coniparatively narrow and in prac* tice it is found that ari-ingr takes place orcr the whole length of the slot. rl`hus ii the air be caused to enter the central space. trom outside the electr des it must necessarily pass through the arcs.

To insure this direction ot the air as Vt'ar as possible a baille Aor partition ot some suitable refractory inaterial is placed in the furnace, over 'the electrodes so as to close or substantially close the space between the electrodes and the turnace. wall. The air inlet at the bottom ot the furnace is preferably of annular torni so that the air irst passes into the inclosed chamber outside the electrodes and is there preheated and thence passes through the arcing gaps into the central space.

rl`he shape ot' the shield-like. plate ot each electrode will ditler in accordance with the number ot electrodes used but in a preferred construction working with three-phase cui'- rent where three electrodes are used` these are set at an angle o f about 120 and are vprovided with triangular curved plates so disposed thaf, when in their operative position they inclose a central space in the form ot an inverted cone. lilith electrodes of this shape the air inlet or inlets can be easily arranged so that the air entering the furnace chamber iii-st passes to the outside of the electrodes and thence through the slots between them and away upiwartl.V

Obviously a stanewhat similar arrangement slightly nioditied could be employed with a tui-nace working en a si -phase circuit.

.lhe shield-like plates ot the electrodes may be wateramoled in any convenient way. Yt'or instance they may he hollow and water may be circulated through 'them or the plates may be cast on to pipes through which water can be circulated. lt is vpreferred to make the lront surface and edges ot' each electrode in the form ot a removable plate so that it can be renewed without ditlicultv.

The baille or partition ot' refractory material above the electrodes may in some cases not entirely close the space between them and the turnace wall. a small opening being lett Vtor the admission ot cooling' air to the tops ot the electrodes. For the same purpose. namely tor cooling the electrodes, the shield-like plates may be provided with holes or slots so that some air may pass into the central space through the body ot the electi-ode.

Atltliouch it is preferred to cause the air to pass from the outside ot the electrodes through the slots or arcingf gaps into the central space vet that arrangement may be reversed and the furnace constructed so that the air is iirst admitted to the central space and then caused to pass out through. the art-ine gaps into the outer annular chamber. ln such a construction the space between the tops of' the. electrodes and the furnace wall would be lett open instead of being closed and the central space between the tops of the electrodes would be closed whollyvor partially by a baille or partition. lVhatever `may be the construction in this respect it struction ol electric vfurnace according to of eiectric furnace also according to this invention. F ig. 6 is a vertical sectional View slmilar to Fig. 5 but showing a mod1 fied construction of air inlet.

The furnaces illustrated by way of 'example are intended to work on a three-phase circuit and thus are provided with three electrodes. Each of these yelectrodes cornprises a hollow shield-like body or plate A. and tubular stems or connections A which pass through the wall B of the furnace and are connected up in any vusual way to the circuit. The shape of tl plates A is such that when the electrodes are in position they inclose a central space roughly in the form of an inverted cone access to that space being afforded atthe bottom z'. e.. the apex of the inverted cone and throngl or spaces G separating one electrode from its neighbor.

In the form sho'wn in Figs. l to 4 the air to be treated is admitted from the bottom of the furnace through a pipe D which, in the example illustrated, is provided with a central plug D so that the air entering passes through the annular space D2 between -the pipe and the plug and thus tends to pass first to the outside of the electrodes. The air thus entering cannot pass away without going through the arc, for the top vof the space in the furnace surrounding the electrodes is inclosed by al baffie E of r'efractory material. Thus the air has to pass into the central space through the slots or spaces C through the arc which fills the space between the electrodes and thence up through the central opening in the baffie E. As the hottest part of the arc is found to be toward the lower part of the electrodes, a second baffle E may be provided to cause the air to enter through the lower portions of the spaces C. This effect isalso assisted by so disposing the electrodes that their upper edges are nearer the wall of the furnace than are the lower edges. In close proximity to the baflie E and preferably adjustably supported relatively to the furnace wall B, is a'steam generator F which is'show'n by way of example as having vertical heating fines F. The functions of a steam generator so placed are well known, namely, to cool the gases quickly and to utilize as far as possible the heat which they give up. The electrodes are conveniently Water-cooled and in the construction shown the hollow plate or body A is provided with a vertical diaphragm A2 extending from the bottom nearly to the top as shown in Fig.

is a plan of the the slots "be provided. Other constructions may be adopted for insuring the cooling of the electrodes for i-nstance, they may be made of plates backed with a coiled tube through which water is circulated.

Tn the furnace shown in Fig. 5 the furnace is made in two parts, the lower portion B forming the chamber into which the air enters, and the upper part B2 coming close around the outside of the electrodes` so that the air is forced to enter the arcing space through the lower portions of the spaces C. This ligure also shows a modified construction of air inlet pipe in which there is a central aperture D3 and side holes D4. These holes D4 are preferably situated in line with the spaces C. The wire G is for the starting spark and is preferably provided inboth forms of furnace.

in a modified construction pipes or nozzles may be provided to lead the air from the openings D* to points just outside the lower portions of the spaces C. Such a construction is illustra-ted in Fig. 6 where pipes or nozzles D5 are shown leading from the air inlet up to the lower extremity of each of the gaps between the electrodes.

The depth and the inclination of the plates forming the electrodes may be varied as is found Adesirable and the dimensions of the spaces C separating,r the electrodes can also b arranged to suit the size of the furnace and the conditions of the circuit from which the power is obtained.'

What I claim as my invention and desire to secure by Letters Patent is zl. In an electric furnace for the fixation of nitrogen the combination of afurnace chamber, electrodes within lsuch chamber so shaped and disposed that they inclose and vwithin Such chamber and so shaped and disposed as to inclose and surround a central space 1n the form of an inverted cone except for comparatively narrow gaps between the edges of adjacent electrodes, anv

inlet for air, and meansfor causing the admitted air to pass through the gaps between the shield-lilteends of the electrodes into and through the central space.

3. In an electric furnace for the fixation of nitrogen the combination al al'furnace chamber, electrodes having shield-like ends withi'nf such chamber and so shaped and .disposed as tofinclose a central space in the form ofen inverted cone an inlet for air near the bottom of the furnace and a baille or partition bet'weenthe upper portions of wall of the furnace a pluralit'vl of electrodes passing' throughl the walls Of such chamber and havingV shield-like. endsfornnnf; an nivel-ted cone with gaps between the electrodes.' an air inletat the bottom of the furnace chamber and a. battle to prevent air from .passingup between the electrodes and the wall of the furnace chzuubc without passing' .into the central" space.'

In an electric furnace for the fixation of nitrogen the combination of a' furnace chamber in the form of an inverted cone, a plurality of electrodes passing` through the walls lof -such chamber andhavinp; hollow shield-lilre ends forming` an inverted cone with gaps between the electrodes, removable face plates to said shield-like ends, an air inlet at the bottom ofthe furnace cham ber and aV balie to prevent air from passing up between tne electrodes and the wall of the furnace chamber Without passing into the central space.

6. In an electric furnace for the fixation of nitrogen the Combination of a furnace chamber in the form of an invertedcone, a plurality of electrodes passing through the walls of such chamber andvhaving shieldlilce ends fornlinp; an inverted Cone with ,gaps between the electrodes, an air inlet at the bottom of the furnace chamber having Openings in line with the gaps between the electrodes and a baflle to prevent air from passing up between the electrodes and'the wall' of the furnace chamber Without pas'sing into the central space.

In testimony whereof I have signed my name to this specification inthe presence of two subscribing Witnesses.

ERNEST KILBUR'N SCOTT.`

vVitnesses: i

ROLAND HEFFORD, GLADYS M. L. JONES. 

